The problem

After you've created your PyCharm project, you'll see that it contains two files of immediate interest.

queens. py$,$ in which you'll find the skeleton of a class named QueensState.

test$\_$queens.py $($in a directory named $),$ in which you'll find the skeleton of a unit test class named TestQueensState that is meant to contain unit tests for

QueensState.

Your end goal is twofold: Implementing the methods of QueensState class meeting the requirements specified in its docstrings and type annotations, and implementing unit tests of

that class in the TestQueensState class.

You might now want to take a look at those two files, so you have an idea of what lies ahead. But it's important that you not barrel forward toward those goals without having read the

rest of this project write$-$up$,$ because there are requirements about how you do this work, in addition to requirements about whether you complete it$.$ While I$\text{'}$m sure all of you have

the skills to complete this task in your own chosen way already, there are learning objectives here that have more to do with tools and techniques $-$ which, for most of you, will be a

departure from what you're used to $-$ than the code we're asking you to write, which may not be new territory for you at all.

Limitations

You can use the Python standard library where appropriate in this project, and you can certainly depend on the code that we've provided, but you will otherwise not be able to use

code written by anyone else other than you. Notably, this includes third$-$party libraries $($i$.$e$.,$ those that are not part of Python's standard library$),$ which are strictly off$-$limits in this

course except where specifically allowed. Colloquially, if we have to install something other than Python, Git, and PyCharm in order for your program to work, it's considered off$-$

limits$,$ unless specific permission is given in a particular project. This project offers no such permission.

Since we'll be automatically testing your

class, rather than relying only on your tests to demonstrate its completeness and correctness, do not modify the

namedtuple or the provided exception classes $($DuplicateQueenError and MissingQueenError$),$ since our automated tests will depend specifically on the way that they're written.